1. Field of the Invention
The invention relates to a unit A to fit a femoral head T prosthesis component or element, and more particularly, however not limitatively, to a unit A selectively fitting a femoral head T onto the corresponding part Ta of a hip prosthesis element.
The femoral shaft is positioned on the neck C of a stem provided for insertion into an internal complementary part Ta of a hip prothesis element by the practitioner during the surgical operation creates a lot of problems.
Spherical shape of the femoral heads makes it difficult for them to be handled. This difficulty is increased by the fact that the surgeon wears moist gloves, which are often covered with blood. Therefore, there are risks of slipping and consequently of dropping the head which may cause damage to the head.
If the surgeon was not to drop the head, this type of handling creates other disadvantages such as:
risk of damaging the surface finish of the head considering that stainless steel can be scratched very easily;
risk of introducing various impurities into the recess of the head which are likely to become trapped inside the head after it has been fitted onto the neck of the prosthesis; and
difficulty in fitting the head onto the neck of the prosthesis which is already introduced into the medullary canal, emphasizing that the femoral head has to be swivelled for its recess to be in front of the neck.
Furthermore, it is understood that such handling operations strongly jeopardize the sterilization of the heads, despite all the precautions initially taken to provide perfect sterilization of the heads before they are to be positioned in place.
2. Description of the Prior Art
This type of implant is known, generally comprise a stem inserted into the centromedullary canal of the femur and a neck destined to take a spherical femoral head. In the majority of cases, this femoral head has a recess complementary to that of the neck of the stem. The recess of the head and the neck are very often tapered.
These known prior uses teach and disclose various types of prosthesis components of sorts and of various manufactures and the like as well as methods of their construction, but none of them whether taken singly or in combination disclose the specific details of the combination of the invention in such a way as to bear upon the claims of the present invention.